Alarm for door-knobs



' UNITED STATES PATENT OFFI E.

MICHAEL TRUBY, OF ELKHART, INDIANA.

ALARM FOR DOOR-KNOBS.

SPECIFICATION formingpart of Letters Patent No. 235,592, dated December14, 1880.

Application filed May 1, 1880. (ModeL) To all whom it may concern:

Be it known that I, MICHAEL TRUBY, of Elkhart, in the county of Elkhartand State of Indiana, have invented a new and valuable Improvement inAlarms for Door-Knobs; and I do hereby declare that the following is afull, clear, and exact description of the construction and operation ofthe same, reference being had to the annexed drawings, making a part ofthis specification, and to the letters and figures of reference markedthereon.

Figure 1 of the drawings is a representation of a top View of myimproved alarm, and Figs. 2, 3, and 4 are details.

This invention has relation to improvements in alarms for door knobs andlatches, which are sounded as often as the knob is turned in the act ofretracting the bolt for the purpose of opening the door.

The nature of the invention consists in certain novel combinations ofparts, as will be hereinafter more fully set forth.

In the annexed drawings, the letter A designates an ordinary door-knob,by the rotation of which the latch B is retracted. Upon the shank o ofthis knob is passed a metallic ring, I), which is fixed thereto by meansof a screw or otherwise, and which is provided with a projecting'flange,1), arranged at right angles to the axis of the said ring, and extendingabout onehalf around the same. At each end of this flange, at its outeredge, is erected a post, 0, upon which is passed a tubularbearing-sleeve, cl, projecting from the end of the cam-plates G, whichthus have free vibration on said posts.

d indicate coil-springs on the sleeve (1, and secured at one end to theflange b, and at the other to the canrplates aforesaid, the object ofwhich will be hereinafter set forth. These cam-plates bear at their freeends upon the flange b, and are widest at this part. Nearer their pointof vibration they are cut away, as indicated at e.

D indicates alever-hammerpivoted to apost,

I), on the door, and actuated to strike the hell 1) by means of aspring, S, arranged between the post and the power end of the lever in atubular box, f. The end of the hammer is provided at its end next theknob with an anti-friction roller, g, that bears against the flange 1),between the free ends of the camplates, when the knob is not in use. Theknob being turned, however, the roller ascends the incline of one of thecam-plates and causes the spring S to be compressed. Upon reaching thecut-away point e of said plate it passes ott' therefrom, suddenlyreleases the hammer, and sounds the alarm violently. The knob, beingreleased after opening the door, returns to its normal position throughthe medium ofa suitable spring. During this return movement of the knobthe cam-plates are drawn past the anti-friction roller, which, beingstationary and bearing against the edge of said plate, causes it toswing upon its pivot and allow the said roller to return to its propernormal position between the ends of the said plates. These latter beingreleased by the roller are swung back and reset by the reaction of thespring (1 in readiness for a subsequent movement of the knob. Theseplates, at their hearing on the flange, are made thin or wedging.

In practice, when not convenient, the collarring need not be secured tothe knob, but may be applied on a supplemental bearing on any part ofthe door, and may be actuated by suitable connections from the knob.

What I claim as new, and desire to secure by Letters Patent, is-- In adoor-alarm, the combination, with a spring-actuated hammer, D, having anantifriotion roller, g, in its power end, and a bell, D", of a ring, I),secured to the door-knob and having the flange I), the inclinedcam-plates O, pivoted to posts erected at the ends of said flange andbearing on said flange at their ends, and the coil spring d returningthe said plates to their places, substantially as specified.

In testimony that I claim the above I have hereunto subscribed my namein the presence of two witnesses.

MICHAEL TBUBY.

Witnesses:

JOHN TRUBY, HENRY V. (loans.

